VRRP/HSRP Multicasting issuse

[vinay_verma80]

Hi expert,

I am facing an isssues with 7609 for LAN switching , based on  LAN (VRRP/HSRP) feature.

Actually  we are having ES+ cards (on 7609) and we are using multiple groups(say  350 vrrp groups) running on the router . the routers are connected as

router 1>>> mux(which is working as switches)>>> router2

my questing are

1.  does their will be "multicast packets" (for VRRP/HSRP group) "from backup  router to Master router", when in stable state( ie when Master and  backup are already chosen) , or the packet from backup to master should  be unicast

I know for sure, the packet from master to back is multicast packets denstination to Multicast IP packet and To MAC address

I am not sure but I think from backup to master it should be multicast

2. what is frequency of these packets( from backup to master)

3.  As i have multiper group on a single interface ( we are using q-in-q),  when the connectivity from router's is broken, then does all the groups  will muticast their active roll in the lan sengment "at once" or it will  be in a groups say 100 groups at once, and after few ms few 100's and  sone ( as is on OSPF or RIP)

Please fin dthe config

for Master router(ES+ card)

interface GigabitEthernet2/1.372

encapsulation dot1Q 2519 second-dot1q 372

ip address 172.25.136.156 255.255.255.224

vrrp 203 ip 172.25.136.158

vrrp 203 timers advertise msec 150

vrrp 203 priority 110

and

interface GigabitEthernet2/1.188

encapsulation dot1Q 2506 second-dot1q 188

ip address 172.25.130.220 255.255.255.224

standby version 2

standby 327 ip 172.25.130.222

standby 327 timers msec 100 msec 150

standby 327 priority 110

standby 327 preempt

For back up

interface GigabitEthernet2/1.372

encapsulation dot1Q 2519 second-dot1q 372

ip address 172.25.136.157 255.255.255.224

vrrp 203 ip 172.25.136.158

vrrp 203 timers advertise msec 150

vrrp 203 priority 90

!

and

interface GigabitEthernet2/1.188

encapsulation dot1Q 2506 second-dot1q 188

ip address 172.25.130.221 255.255.255.224

standby version 2

standby 327 ip 172.25.130.222

standby 327 timers msec 100 msec 150

standby 327 priority 90

standby 327 preempt

we are in between troubleshooting I hope we get the ans( Actul problem we are seeing in the router's that we have 2 ports on active routers and 2 ports on standby router , but we are not seeing muticast on 1 port on standby router where as all other 3 ports are seeing multicast packets)

Thanks in advance

Warm regards

Vinay Verma

[nkarpysh]

Hi Vinay

If this is still relevant? You can send me a personal message I can try to help further.

Nik

[vinay_verma80]

HI this isssue is still relevent

And i am still looking for solutions

[nkarpysh]

Hi Vinay,

Answering to your questions:

1. In HSRP btoh active and standby send hellos to MCAST address 224.0.0.2 or 224.0.0.102 (V2) - this is done for the case of more than two routers in HSRP group - those also should now that standby is active and take it's role in case of standby failure. By default Hello is in each 3 seconds, Dead interval is 10 seconds.

VRRP a bit different:

VRRP routers send Hello messages to IP Multicast address 224.0.0.18. The frequency with which the Master sends Hello messages is the Hello Interval. Only the Master sends Hello messages. However, a Backup uses the Hello interval you configure for the Backup if it becomes the Master.

The Backup routers wait for a period of time called the Dead Interval for a Hello message from the Master. If a Backup router does not receive a Hello message by the time the dead interval expires, the Backup router assumes that the Master router is dead and negotiates with the other Backups to select a new Master router. The Backup router with the highest priority becomes the new Master.

2. HSRP - each 3 seconds by default (Hello interval)

VRRP - na

3. Each group was configured at different time - you can see bu "show standby group NUM" the current expiration time. So if you lose master  -each group will wait for it's expiration time and only then try to become master and start sending Hellos if it did not like in VRRP. In HSRP again after expiration time if not Hello received it will also atke the master role. So all groups can't change in a same momet of time because they started all in different times and have different expiration intervals.

Hope this helps,

Nik

[vinay_verma80]

thanks, I will get these thing tested and will get back to you , but here I have a question which is in continuation of above

Actually this is being used for 3 G , and their are 2 ports on a routers( 2 on Master router and 2 on backup router).

A). Toplogy

The connecting is as

Master router>>>. Mux(L2 ethernet )>>> Backup router

{ their is a y cable from mux to router }

1. At Both port on Mux end which is connected Master Router , we are seeing Multicast packets ( ie Mux is receving multicast packet)

2. At one port(port 1) On Mux which is connected Back Router, we are seeing Multicast packet ( ie Mux port1  is receving multicast packet)

but

on another port(port 2) On Mux which is connected Back Router, we are not seeing Multicast packet ( ie Mux port2 is receving multicast packet)

B) Problem

1. when we shutdown the  Master router port1 ( connecte to Mux port1), then the traffic shift imediatly to Backup  router port1( no delay)

and

when Master router port1 is unshut the traffic comes imediatly back to Master router port 1 ( no delay)

2. But  when we shutdown the  Master router port2 ( connecte to Mux port1), then the traffic shift imediatly to Backup  router port2( no delay)

and

when Master router port2 is unshut the traffic comes doesnot come  imediatly back to Master router port 1 ( delay of 15 sec or more)

C). Query

1. can you try to explain ( see point A) why we are reciving mulicast packet at Backup port 1( Mux port conncet to Backup router port 1) and why we are not seeing mulicast packet at Backup port 2( Mux port conncet to Backup router port 2)

2.for point B) can u explance what could a problem for dealy of 15 sec or more when the router switch back from BAckup router port 2 to Master router Port

1( and  why we are not seeing the same behaviour) in port 1

Hopefull u/ somebody could help

Warm Regards

Vinay Verma

[nkarpysh]

Hi Vinay,

It is try to guess not seeing particular config on port connected to MUX and on VLAns. Can you please share those.

Thanks,

Nik